JPS6254013A - Method and apparatus for melting scrap - Google Patents

Abstract

PURPOSE:To reduce cost and to improve productivity by subjecting the scrap in a furnace body to initial melting by an arc, storing a prescribed amt. of the molten scrap, blowing a carboneous material and oxygen into a molten steel and melting the remaining scrap by the combustion energy generated by the combustion of CO. CONSTITUTION:The scrap in one of the plural furnace bodies is initially melted by the arc and a prescribed amt. of the molten steel is stored in one furnace body by the initial melting. The carboneous material and oxygen are blown into the molten steel to generate the combustion energy by the combustion of CO. The remaining scrap in the one furnace body is melted by such combustion energy. The heating of the scrap in the other furnace body is executed by the combustion of the CO in the waste gas generated by the initial melting or the waste gas contg. the CO and the preheating of the scrap in the one furnace body is executed by the waste gas from the other furnace body.

Description

[Detailed Description of the Invention] Field of Industrial Application] The present invention relates to a scrap melting method and apparatus that are capable of saving power and energy, reducing steel manufacturing costs, and improving productivity. It is.

[Prior Art] Ordinary arc furnaces for steelmaking rely almost entirely on electrical energy for scrap melting energy, with only some supplementary energy being supplied by an oxygen burner. In addition, as an energy-saving measure, a two-furnace exchange system is adopted as shown in Figure 4, heating and melting the scrap alternately, and exhaust gas generated during melting in one furnace body a is transferred to the connecting duct. so that it is introduced into the other furnace body C via b,
The scrap d in the furnace body C is preheated and heat is recovered. In the figure, e is an electrode, f is an exhaust gas duct, and (1, g+ is a furnace lid.

[Problems to be Solved by the Invention] However, in the above-mentioned arc furnace for steelmaking, the melting energy is largely dependent on electric energy, resulting in large power consumption and increased steelmaking costs. In addition, the heat recovered by preheating the scrap with exhaust gas is usually about 5 to 15% at most, because the exhaust gas from the furnace body has a large temperature change and an average low temperature level.
In the profiles of the furnace bodies a and b, the exhaust gas duct f is connected to the furnace M.
(Since it is installed at J', the exhaust gas takes a short path through the scrap d of the furnace main body for preheating, and the convection electric heating effect is not good.

In view of the above-mentioned circumstances, it is an object of the present invention to reduce power consumption, save power and energy, reduce costs, and improve productivity.

[Means for Solving the Problems] The present invention involves initially melting the scrap in the furnace body using an arc, and when a predetermined amount of molten steel accumulates in the furnace body due to the initial melting, carbonaceous material and oxygen are injected into the molten steel to remove CO. is configured to generate combustion energy by combustion of the furnace body, and melt the remaining scrap in the furnace body with the combustion energy, and initially melt the scrap in one of the plurality of furnace bodies by an arc, When molten steel accumulates in a predetermined amount in one furnace body due to initial melting, carbonaceous material and oxygen are injected into the molten steel to generate combustion energy by combustion of CO, and the remaining scrap in the one furnace body is used to generate combustion energy. A configuration in which the scrap in the other furnace body is heated by the combustion of CO in the exhaust gas generated by the initial melting or the exhaust gas containing CO, and the scrap is preheated by the exhaust gas from the other furnace body. It is equipped with

[Function] In the present invention, carbonaceous material and oxygen are supplied into molten steel after the initial melting of scrap in a predetermined furnace body by an arc, and the remaining scrap is melted by the combustion heat of CO generated by the reaction of carbonaceous material and oxygen. Melting is performed, and the unmelted scrap of the furnace body is heated to a high temperature or semi-molten state by the combustion heat of CO in the exhaust gas and CO in the exhaust gas after the heating, and the exhaust gas after heating The scrap in the scrap preheating tank is preheated.

[Example] Hereinafter, an example of the present invention will be described with reference to the accompanying drawings.

Figures 1 to 3 show an embodiment of the present invention, in which a portion of the upper taper of the furnace bodies 1a, lb arranged at a required interval is connected by a connecting duct 2, and the upper and lower parts of the furnace bodies 1a, lb are connected by a connecting duct 2. The overhanging parts 3a, 3b that project in mutually opposite directions are provided with furnace bottom tapping ports 4a, 4b, and are also provided with exhaust gas outlets 5a, 5b.
Exhaust gas duct 6a connected to.

6b is connected to an exhaust gas duct 7, from which exhaust gas from the furnace body 1a or 1b can be supplied to the scrap preheating tank 8 from the top. Furnace body 1
The upper space of a, II) is large enough for CO gas combustion, and exhaust gas can be discharged from the lower part of the scrap preheating tank 8.

Approximately midway between the furnace bodies 1a and lb, there is a furnace cover attachment/detachment device 9.
is installed. The furnace cover 1152 device 9 has a point
A frame 10 is provided which can be rotated horizontally around the center, and a lifting device (not shown) attached to the frame 10 for lifting and lowering an arc melting furnace M12 provided with an electrode 11 is provided.

Rails 13a, 1 laid on the left and right sides of the furnace body 1a, lb
3b, the furnace lid attaching/detaching device 14a, 14b is attached to the furnace body 1a,
The frames 15a and 15b of the furnace cover removal devices 14a and 14b are arranged so as to be able to approach and move away from the furnace cover removal device 1b.
An elevating device (not shown) for elevating and lowering the heating furnaces 116a and 16b is provided.

In the figure, 17a and 17b are nozzles installed on the bottom of the furnace body 1a and lb for injecting carbonaceous materials such as coke and coal and oxygen, and 18a, 18b, 19a and 19b are installed on the side wall of the furnace body 1a and lb. burner, 20a, 20
21a and 21b are nozzles for oxygen injection provided in the furnaces 116a and 16b, 22 is a valve provided in the connecting duct 2, and 23a and 23b are Valves installed in the exhaust gas ducts 6a and 6b, 24 a valve installed in the duct 7, 25 a power transformer, 26a and 26b scraps in the furnace body 1a and 1b, and 27 molten steel.

For example, when scrap 26a is melted in the furnace body 1a, scrap 26b is heated in the furnace body 1b, and the scrap is preheated in the scrap preheating tank 8, the furnace lid attaching/detaching device 9 is moved clockwise in FIG. The furnace body 1a is rotated to be shielded by the furnace i12, the electrode 11 is inserted into the furnace body 1a, the furnace lid attachment/detachment device 14b is advanced toward the furnace body 1b side, the furnace body 1b is sealed by the furnace M16b, and the valve 22 .23b
, 24 is opened, the valve 23a is closed, and the electrode 11 is energized by the power transformer 25 to start melting the scrap 26a in the furnace body 1a by arc. At this time, burners 18a and 19a may be used together.

The gas generated by melting the scrap 26a is introduced into the furnace body 1b from the connecting duct 2 from the top of the furnace, and after heating the scrap 26b, is passed through the overhang 3b into the exhaust gas duct 6.
b, and introduced into the scrap preheating tank 8 through the exhaust gas ducts 6b, 7, and after preheating the scrap in the preheating tank 8, it is sucked by a blower (not shown) and discharged to the outside.

After the arc power is turned on, when approximately 30% of the scrap 26b in the furnace body 1a is melted and molten steel 27 accumulates at the bottom of the furnace, the power transformer 25 is shut off to stop melting by the arc, and the furnace lid is removed by the furnace lid attaching/detaching device 9. 12 is removed from the furnace body 1a and moved to the standby position, the furnace lid attaching/detaching device 14a is operated to shield the upper part of the furnace body 1a with the furnace 116a, and the molten steel 27 is removed from the furnace body 1a and moved to the standby position.
Carbon material and oxygen are blown into the inside from the nozzle 17a to melt the scrap 26a. The CO gas generated by injecting carbonaceous material and oxygen is partially combusted by the oxygen injected into the furnace body 1a from the nozzles 20a, 21a, etc., and the combustion energy is used to melt the scrap 26a and raise the temperature of the molten steel 27. The remaining CO-containing exhaust gas that has contributed to the refining process is transferred to the connecting duct 2.
The scrap 26b is introduced into the furnace body 1b and heated to a high temperature or semi-molten state, and then discharged from the furnace body 1b and introduced into the scrap preheating tank 8, where it is used for preheating the scrap.

When all the scraps 26a in the furnace body 1a have been melted and the temperature has risen to a predetermined temperature, the melting in the furnace body 1a is stopped, and the furnace bottom tapping port (not shown) is opened to draw the molten steel. Drain into a ladle. Furthermore, after the melting and discharging of molten steel in the furnace body 1a is completed, the furnace 11 is
6a and 16b are removed from the furnace bodies la and lb, and the furnace lid attachment/detachment device 9 is operated in the counterclockwise direction in FIG.
Remove the scraps from the furnace body 1a using a crane or a special trolley.
The furnace main body 1a is shielded with the furnace lid 16a by the furnace lid attaching/detaching device 14a, the scrap is put into the scrap preheating tank 8, the valves 2.23a and z4 are opened, and the valve 23 is
b is closed, and the scrap 26b is melted in the furnace body 1b, the scrap 26a is heated in the furnace body 1a, and the scrap is preheated in the scrap preheating tank 8 in the same manner as described above.

As mentioned above, scrap is preheated in the scrap preheating tank 8 using exhaust gas, heated in one of the furnace bodies 1a and lb by combustion of exhaust gas or CO gas from the other furnace body, and heated in the other furnace body. By performing initial melting with arc power and melting remaining scrap with carbonaceous fuel and raising temperature, power consumption when arc power is applied is 150%.
KW! It is about l/T, and the conventional power consumption is 400 to 5
It decreases significantly compared to 00/■. Therefore, steel manufacturing costs are reduced and productivity is improved.

It should be noted that the present invention is not limited to the above-mentioned embodiments, but also that it can be implemented with a single main body, that it can be implemented even with a plurality of scrap preheating tanks, that it does not require a burner, and that Of course, various changes may be made without departing from the spirit of the invention.

[Effects of the Invention] According to the scrap melting method and device of the present invention, <I> Much of the electrical energy can be replaced with inexpensive carbonaceous energy, making it possible to save power and reduce production costs. <n> Sensible heat of CO gas generated in molten steel can be effectively used within this system, contributing to energy saving. <1> Overhang provided at the bottom of the furnace body for gas introduced from the top of the furnace body. It has various excellent effects, such as the ability to heat scrap efficiently as it can be discharged from a It can be played.

[Brief explanation of the drawing]

Figures 1 to 3 are explanatory diagrams of one embodiment of the present invention. Figure 1 shows the initial melting of scrap using an arc in one furnace body, and the exhaust gas used to heat the scrap in the furnace body. An explanatory diagram for preheating scrap. Figure 2 shows a method in which CO gas is combusted with oxygen in one furnace body, the scrap is melted and heated by the combustion energy, and Co in the exhaust gas is combusted with oxygen in the other furnace body. The combustion energy is used to heat the scrap to a high temperature or semi-molten state, and the scrap is preheated in a preheating tank. FIG. 3 is a plan view, and FIG. 4 is an explanatory diagram of a conventional example. In the figure, 1 is the furnace body, 2 is a connecting duct, 3a, 3b are overhanging parts, 6a, 6b, 7 are exhaust gas ducts, 8 is a scrap preheating tank, 11 is an electrode, 17a, 17b, 20
a, 20b. 21a and 21b are nozzles, 25 is a power transformer, 26a
, 26t) indicates scrap, and 27 indicates molten steel.

Claims (1)

[Claims] 1) Initial melting of scrap in the furnace body using an arc,
When a predetermined amount of molten steel accumulates in the furnace body due to initial melting, carbonaceous material and oxygen are injected into the molten steel to generate combustion energy by burning CO, and the remaining scrap in the furnace body is melted with this combustion energy. A scrap melting method characterized by: 2) The scrap in one of the multiple furnace bodies is initially melted using an arc, and when a predetermined amount of molten steel accumulates in one of the furnace bodies due to the initial melting, carbonaceous material and oxygen are injected into the molten steel to remove CO. Combustion energy is generated by combustion, the remaining scrap in the one furnace body is melted by the combustion energy, and the other furnace body is melted by combustion of CO in the exhaust gas or CO-containing exhaust gas generated by the initial melting. A scrap melting method characterized by heating the scrap inside and preheating the scrap with exhaust gas from the other furnace body. 3) A plurality of furnace bodies equipped with carbon material and oxygen blowing nozzles, connected at the top side by a connecting duct, and in which the top of the furnace can be shielded with a furnace lid equipped with an electrode or a furnace lid without an electrode; 1. A scrap melting device characterized by being provided with a duct connected to an overhanging part of the bottom of the furnace body and capable of supplying exhaust gas to a scrap preheating tank.